This invention relates to truck bodies. More particularly, this invention relates to methods and apparatus for providing and strengthening co-polymer truck bodies.
U.S. Pat. No. 5,820,718, commonly assigned, describes a liquid storage tank having high strength properties resulting from the use of bended co-polymer sheets having extrusion welds to fuse material into the interior corner of some or all of the bend junctions. U.S. Pat. No. 5,820,718 (the ""718 patent) is incorporated by reference herein, in its entirety as if its entire disclosure was written herein. The copolymer described in the ""718 patent is marketed under the tradename xe2x80x9cpolyprene,xe2x80x9d and is an extruded composition of polypropylene polyethylene with carbon introduced in the extrusion for UV protection. The technical descriptions and aspects of the polyprene are included in the ""718 patent are not repeated herein, for the sake of brevity.
As described in the ""718 patent, the copolymer material may begin as a sheet which is bent on a bending machine. After the bending machine places the sheet into a predetermined angle position, an extrusion weld is placed in the interior corner of the bend junction to provide reinforcement and strength. The extrusion weld reinforces the material from any reduction of the physical properties of the material that may occur during the bending process. The extrusion weld is different from other welds, such as the triple weld which suffers the disadvantage of re-heating the plastic walls after each weld rod is put down, and the triangular weld which does not utilize an automatic extrusion welder and must be hand fed by the operator.
U.S. Pat. No. 5,979,686 (the ""686 patent), commonly assigned, also described the bent copolymer sheet with the interior extrusion weld. Both the ""718 patent and the ""686 patent describe the joint in the context of creating large liquid storage tanks, such as those used on fire engines, etc.
The present invention extends and improves upon the application of the bent copolymer, extrusion weld technology described in the ""718 patent and the ""686 patent beyond a liquid storage tank included on a fire engine, to the fire engine body (or other truck body) itself. Due to the high reliability and strength of the extrusion weld junction described in the ""718 and ""686 patents, the junction finds excellent application on the truck body itself, when the truck body is created out of copolymer material.